The present invention relates to an MAP (Monophasic Action Potential) catheter adapted to be inserted into the endocardiac cavity for the purpose of measuring the action potential of the myocardiac cells by means of a pair of electrodes. One electrode is situated in the end surface of the catheter body and is brought into contact with the endocardiac surface, and the other on the outer peripheral surface of the catheter body, proximal to the distal end.
This pressure type MAP catheter has recently been developed and is taking the place of the suction type since the latter can injure the myocardium when used for a long period of time and involves a structure and an operation which are rather complicated.
However, its electrodes are formed as masses although they are of the Ag-AgCl line type. As shown in FIG. 6, one electrode 1 of this conventional pressure type MAP catheter is partially projecting from the tip of the catheter body 2, and the other electrode 3 is exposed through a hole made in a peripheral surface 2a in the tip section, both electrodes being secured in position by means of cement 4 ("THE AMERICAN JOURNAL OF CARDIOLOGY", vol. 51, June 1983, on page 1631).
This structure requires Ag which is an expensive material in an amount corresponding to the spherical configuration of the electrodes. Further, there is the danger of the endocardium being injured since the cement section 4 is directly pushed by a guide wire 5 through a sheath 6. Besides, the hole 2b provided in the peripheral surface 2a in the distal section is liable to be clogged up with foreign matter, resulting in the electrode being in a poor contact with blood.